The present invention relates to rules used in conjunction with die boards and more particularly to a rule design having a group of notches formed in the lower portion thereof where the notches serve to bridge portions or sections of the die board.
Various types of rules are customarily used in cutting dies. In the way of examples, these rules may include perforating, scoring or cutting rules. In any event, these rules are typically inserted within slits formed in a die board that forms a part of a cutting die. Typically a die board is designed such that it extends over a cylinder or plate structure and these slits extend completely through the die board such that once a rule is inserted therein, the rule may in fact engage the underlying cylinder or plate structure. In order to keep the die board together and prevent the die board from falling apart like a puzzle, it is customary to leave sections of the slit uncut. It is appreciated that the rules will have to be notched in order that they might be able to bridge these uncut sections within the slits. To deal with this, it is customary for a die maker to cut bridging notches in the lower portion of the rules before inserting them into the respective slits of the die board. That is, the die maker will typically measure the slits and determine precisely the locations of the uncut sections within the slits that have to be bridged. Once this is done, then the die maker will proceed to cut bridging notches in the lower portions of the rule such that the bridging will appropriately line-up with the uncut sections that lie in the slits of the die board. However, it is no small undertaking to cut bridge notches in a set of rules. Indeed, it is not unusual for a typical rotary die board used for cutting corrugated board, for example, to include 700 inches of rule and approximately 200 individual bridges or notches formed in the rule. Not only are there many notches to be cut, but each individual notch or bridge requires substantial time and effort on the die maker""s part. Cutting bridge notches in rules is for the most part a laborious manual operation that requires a substantial amount of time and effort. Furthermore, in cutting bridge notches in rules, the bridge notch usually is formed in a square or rectangular configuration. When such bridge notches are introduced into the rule, there is also introduced new stress points about the upper corners of the bridge notches.
Further, it should be appreciated that in the case of rotary die cutting machines, the die board assumes a generally arcuate or curved configuration. Accordingly, it is not unusual for the rules, whether they be perforating, scoring or cutting rules, to be curved or arcuate shaped. To facilitate the curving of these rules, it is common practice to cut very small notches in the lower portion of rules prior to the rules actually being curved. That is, the rules are ordinarily fabricated in a straight configuration. Thereafter, the small notches are formed in the lower portion of the rules and thereafter the rules are curved. The presence of the small notches in the lower portion of the rules generally facilitates the curving of the rules.
The present invention entails a rule for a cutting die that includes preformed bridging notches that are generally uniformly spaced to span uncut sections of slits formed in a die board. More particularly, the rule includes an upper edge, lower edge, and a main body extending between the upper and lower edges. The bridging notches extend through the lower edge into the main body of the rule. Consequently, the bridge notches are opened from the bottom or along the lower edge of the rule.
The bridge notches may form any one of a number of functions. First, the notches may facilitate the formation of a curved rule. That is, in forming a curved or arcuate-shaped rule, that process or method begins with forming a straight or horizontal rule and then curving the rule. By forming notches within the lower portion of the straight rule, the straight rule is easier to curve.
Secondly, these rules are designed to fit within the slits cut within a die board of a cutting die. Because the slits are normally open to an underlying cylinder or plate, for example, it is important that sections within the slits remain uncut so as to hold the die board together and keep the die board from falling apart like a puzzle. However, these uncut sections appearing at intervals within a slit must be bridged or spanned when the rule is inserted therein. Thus, these bridging notches formed in the lower portion of the rule function to span the uncut sections that lie at selective intervals along the slits.
Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention.